This invention relates generally to pressure wave superchargers for internal combustion engines and in particular to pressure wave superchargers having increased efficiency, emissions control and sound suppression capabilities.
Pressure wave superchargers have been produced, primarily for use on diesel engines, since 1923. The original system utilized a cylindrical rotating member having a plurality of conduits running lengthwise. Exhaust gases from the diesel engine exhaust manifold were directed into one end of the cylinder while incoming fresh air from the air intake vent was directed into the other end of the cylinder.
The fresh air contained in the rotating cylinder conduits was compressed and directed into the air intake manifold of the engine by the high sonic velocity exhaust gases. The exhaust gases were then expelled into the outside atmosphere by the reflected shock wave action of the gases to allow entry into the rotating member of fresh air entering from the air intake vent.
The action of the incident and reflected exhaust gas shock waves were used to compress the air and help expel the exhaust gases before the exhaust gases could pass completely through the rotating member.
In the pressure wave superchargers of the prior art the plurality of conduits forming the rotating member were originally arranged in single ring. This configuration resulted in loud "siren" noises in the 4 kHz range. To help reduce, but not necessarily eliminate, this noise, the cross-sectional area of the conduits were modified and the conduit openings were arranged in two concentric rings and offset to provide half cycle sonic interference.
Because of the large size of the rotating member openings and the relatively high rotational velocity (up to approximately 9,000 RPM) the rotating member was required to be fabricated using expensive centrifugal investment casting methods.
Later improvements were made in the pressure wave supercharger at low engine speeds by provided an independent means for rotating the rotating member.
Further improvements were made to increase operating efficiency for a range of speed by providing gas expansion pockets in the housing proximate the ends of the rotating member.
For the most part, pressure wave superchargers of the prior art were used on diesel engines, rather than gasoline engines, to improve efficiency and increase horsepower.
Their use on gasoline engines, particularly rotary engines, has not been prevalent because of the high engine RPM, high exhaust temperature and noise suppression requirements, when compared with diesel engine operating characteristics. In addition, the current air pollution standards for diesel engines are not as stringent as for gasoline fueled internal combustion engines that might suggest the use of a catalytic converter to process diesel engine exhaust gases.
None of the prior art references appear to have considered the use of the heat of combustion of unburned fuel as a means of augmenting the supercharging of a gasoline fueled internal combustion engine. Nor have the prior art devices considered the use of permanent magnet, direct current electric drive motors to regulate the speed and eliminate the power drain of the rotating member.